Methods using selector screens in conjunction with interlaced images to provide special visual effects to the unaided eye are well-known and have been in use for some time now to create such special effects as autostereoscopic images (3D) or multiple images angularly separated so that a different image is seen from different perspectives. Such methods differ in the structure of the selector screen and the way in which the images are formed and optically registered with the screen. In common use as screens are parallax barrier strips and lenticular arrays. To separate the available images for presentation to the eye, barrier strips rely on occlusion while lenticular arrays operate by refraction. Even though individual screen mechanisms may differ, all nevertheless fundamentally act as an intermediary between the viewer and the available images to select what is displayed to each eye from different perspectives.
Parallax barriers consist of a series of alternating fine opaque stripes and slits that are parallel to one another. Typically, the slits are transparent regions in an otherwise opaque substrate. The barrier is usually forward of the plane containing the interlaced images whose spatial frequency is arranged in correspondence with that of the barrier's alternating stripes and slits so that one or more left and right stereo pairs are presented, respectively, to the left and right eye for orthoscopic or normal stereographic images or completely arbitrary images may be similarly presented where different messages are to be conveyed along different angles of projection. Alternatively, pseudoscopic images where depth relationships are reversed may be formed by reversing the correct orientation of left and right stereo image pairs images.
Parallax barrier displays are capable of high-quality imagery and, in the case of autostereographic images, have an advantage over other techniques because they do not require the viewer to use visual aids to sort out stereo pairs. Their main disadvantage is that their opaque regions inherently block light from illuminating the image while performing their image selection function. Consequently, the images are typically dim and usually require back lighting of some sort to make up for deficient front illumination.
Lenticular arrays do not suffer from the brightness problems of the barrier systems. These typically consist of a series of parallel cylindrical lenses that are rolled or embossed on plastic or injection molded. Parallel light enters from the front surface, focuses on the focal plane behind each lenticule, is modulated by the image resident there, and returns back out through the lenticule along predetermined angles of separation corresponding to the interlacing scheme preselected to provide autostereographic or multiple image effects.
Both types of screens require more or less precise registration of the interlaced images with the screen structural features to provide the desired visual effect and the demands on tolerancing increases with the number of images and the length of the screen elements whether barrier or lenticule. To achieve the degree of registration required, a number of approaches have been used. Where the images are to be formed on photographic materials such as light sensitive emulsions or photoresistive materials, the images are typically formed in place, in situ, by exposing first one and then the other through the screen from angular locations in front of the screen corresponding to the angular perspectives from which the different images are to be observed. After exposure, the images are developed or otherwise converted from latent images to visible ones, and the images are more or less perfectly registered because they have been exposed in a completely reversible way. In situ exposure techniques suffer from the liability that they require a great deal of time and special equipment to make, and the images and screen are permanently joined together.
Other faster techniques, such as those described in U.S. Pat. Nos. 5,113,213 issued to Sandor, et al. on May 12, 1992 and entitled COMPUTER-GENERATED AUTOSTEREOGRAPHY METHOD AND APPARATUS and its reissue Re. No. 35,029 issued on Aug. 29, 1995 rely on high-speed web-process in which preprinted interlaced images are merged with lenticular arrays. The interlaced images themselves are generated by a computer and reproduced via a high-resolution printing process. Here, the substrate on which preprinted images are formed is provided with a guide line that is monitored via feed back techniques to assure that the longitudinal axes of the lenticules are aligned with the guide line which is, in turn, aligned with the lengthwise orientation of the interlaced images. The lenticules are formed in a softened uv-curable plastic just prior to being mated with the interlaced images and after the two are brought together, the lenticules are exposed to uv-radiation to harden them in place over the interlaced images. Again, the images and lenticules form an integrated whole that can not be separated without damage, and such a process is not amenable to making structures that perform integral packaging functions along with imaging functions.
Sekiguchi, et al. in U.S. Pat. No. 5,494,445 issued on Feb. 27, 1996 entitled PROCESS AND DISPLAY WITH MOVEABLE IMAGES describe a computer based process in which images are cut and pasted while viewed on a monitor to form interlaced images which are afterwards printed. Here, the process requires the images to be observed while being manipulated and original image content is inherently discarded.
It is thus a primary object of the present invention to provide a process for fabricating images for producing special visual effects when coupled with lenticular products that can act as displays or part of a packaging system.
It is another object of the present invention to provide a method by which original images can be reassembled as composite special effects images by resampling procedures that preserve original image content.
It is yet another object of the present invention to provide techniques by which special effects images can be generated easily for use with preformatted lenticulated plastic products particularly suitable for mass distribution.
Other objects of the invention will, in part, be obvious and will, in part, appear hereinafter when the following detailed description is read in conjunction with the drawings.